Onion Plan Session at the 2023 Costa Rica in-person meeting

Do an Onion Plan Session at the Costa Rica in-person meeting.

Some ideas:

1. Progress since 202209MeetingOnionPlan.
2. Try to cover more the Health Roadmap.

Tasks:

• Build a slide deck.
• Do the session, making sure that some people take notes.
• Edit and upload the session notes.
• Follow ups and next steps. Moved into tpo/onion-services/onionplan#5.